Respected Sir/ Madam,
I am _________ (name) and I am working as __________ (designation) in your company and my employee ID is ________.
I am writing this email to inform you that I will not be able to come to the office today, i.e. __/__/_____ (date) as my pet died on __/__/_____ (date).
This is to request you kindly sanction bereavement leave for the said date. I expect your quick response in this regard.